Hi i am looking for some advice on extending a fence i have already in my back garden i am looking to increase the height up to 6 feet and seen as the post currently are solidly in the ground i was wondering if anyone has any tips or advice on how i could make this possible without digging up the old posts? I have heard about extension brakcets but i cannot seem to find any in a 4" size they all seem to be for 3" posts.